In recent years, optical disks under various standards have been being developed and becoming prevalent. For example, CD-ROMs/DVD-ROMs, which are read-only optical disks; CD-Rs/DVD-Rs, which are write-once type optical disks to which data can be written only once; DVD-RAMs and CD-RWs/DVD-RWs, which are rewritable optical disks; and the like are widely known.
Among the optical disks, there are some optical disks which have an area called BCA (Burst Cutting Area). For example, a DVD-RAM or DVD-ROM has a BCA at the innermost peripheral position of the optical disk. A BCA has a bar-code like pattern, which allows identification information for identifying the optical disk to be recorded. This pattern is recorded already at the shipment of the product. An optical disk apparatus reads such identification information before beginning a recording or reading of other information, thus being able to utilize it for the generation of encryption keys, or determine whether playback is permitted or not.
Hereinafter, a procedure of reading identification information which is recorded in a BCA using a conventional optical disk playback apparatus will be described.
FIG. 1 shows an operation procedure of a conventional optical disk playback apparatus. For example, Patent Document 1 discloses an optical disk playback apparatus which operates in accordance with the procedure shown in FIG. 1. First, at step S1, an optical disk is inserted in the optical disk playback apparatus. At step S2, the apparatus begins optical servo for the optical disk, and at step S3 begins to read address information (ID) from the optical disk. Then, at step S4, it moves to a management information position (area) by utilizing the ID, and at step S5 reads management information. Since it is possible to read management information, the position of the management information is determined. Since it is stipulated in the standard that the management information should be disposed at a specific radial position toward the outer periphery from the BCA, the apparatus is able to reach the BCA position by moving a specific distance toward the inner periphery from the position of the management information at step S6. Then, at step S7, the identification information in the BCA can be read.
The reason why the BCA is not directly accessed but is accessed by way of the management information area is that no address can be stably determined within the BCA because the identification information in the BCA is added by processing an area of the optical disk. Note that, from any position toward the outer periphery from the BCA, a movement can be made to the management information position without going by way of the BCA.
On the other hand, the identification information which is recorded in the BCA can also be read by other techniques. For example, in an optical disk playback apparatus which is described in Patent Document 2, a switch is provided at a designed position of an optical pickup which is taken when radiating light toward the BCA. The position of the BCA can be detected by utilizing this switch, and thus the identification information can be read.    [Patent Document 1] Japanese Laid-Open Patent Publication No. 10-228713    [Patent Document 2] Japanese Laid-Open Patent Publication No. 2003-331436